This paper presents an optimal design approach of power system stabilizer (PSS) using multiobjective genetic algorithms. The PSS design is formulated as a multiobjective optimization problem which involves two conflicting performance criteria: the robustness and the transient performance of the closed-loop system. The proposed approach is applied to a single-machine infinite-bus system considering the conventional speed-based lead-lag PSS and a dual-input PSS which uses the accelerating power as an additional input. The optimization results show that trade-offs exist between the two objective functions of the problem resulting in a set of optimal solutions rather than a unique optimal solution. It is also found that the best trade-off according to Pareto dominance is provided by the dual-input PSS.

Keywords: Dual-input power system stabilizer, Robust design, Non-dominated sorting genetic algorithm-II, Single-machine infinite-bus